Capacity controlled relay



Filed Sept. 15, 1928 2 Sheets-Sheet l C a fi/emsuzrsca April 25, 1933.c. o. BARBULESCO 1,905,332

CAPACITY CONTROLLED RELAY Filed Sept. 13, 1928 2 Sheets-Sheet 2 PatentedApr. 25, 1933 UNITED STATES OONSTANTIN D. BARBULESCO, OF

DAYTON, OHIO, ASSIGNOR TO PAUL S. EDWARDS, OF

DAYTON, OHIO CAPACITY CONTROLLED RELAY Application filed September.13,1928. Serial No. 805,754.

(GRANTED UNDER THE ACT E5301! 3, 1883, AS'LMENDED APRIL 30, 1928; 370 0.G. 757) The invention described. herein, if patented, may bemanufactured and used by or the tube.

i may be incident to m for the Government for governmental purposes,without the payment to me of any royalty thereon.

This invention relates to reactance controlled relays and has referencemore particularly to ultra sensitive relays operated by extremely smallvariations in the reactance of an insulated metallic body associatedwith electrical circuits having capacitance, inductance and reactance.

- The invention broadly comprehends a three electrode vacuum tubeassociated with a special electric circuit coupled to a syslem ofmetallic plates or wire. The ensemble is so adjusted that smallvariations in the reactance of the plates or wires, forming what ishereafter termed the external circuit produce great variations in theplate current of These variations can control in turn any mechanicaldevice by sending'the plate current through an electro-magnet or othertransmitting or indicating devices. The tube is associated with aconstant frequency oscillating circuit such as disclosed in applicantscopending application, Serial No. 305,7 53, filed September 13, 1928.

An object of this invention is to produce great variations in the platecurrent of a vacuumtube by very small changes in the capacitance,inductance or reactance of metallic bodies associated with the tube bymagnetic, capacity or direct coupling.

Another object of this invention is to produce an ultra sensitivereactance'controlled relay which can be operated by extremely smallvariations in the reactance of insulated metallic bodies or inassociated electrical circuits having capacitance, inductance andreactance.

Still another object of this invention is to produce a remote controldevice for the operation of mechanical or electrical sequences that isresponsive to small variations in the reactance of an associated systemof metallic plates or wires.

With these and other'objects in view which improvements, the inventionconsists in t e parts and combina-- tions to be hereinafter set forthand claimed, with the understanding that the several necessary elementscomprising my invention may be varied in construction, proportions andarrangement, without departing from the spirit and scope of the appendedclaims.

In order to make my invention more clearly understood, I have shown inthe accompanying drawings means for carrying the same into practicaleffect, without limiting the improvements in their useful application tothe particular constructions, which, for the purpose of explanation,have been made the subject of illustration.

In the drawings, in which the same reference numerals designate similarelements throughout:

Figure 1 is a diagram of one practical arrangement of my improvedcircuit.

Figure 2 is a diagram of a modified form of my improved circuit.

Figure 3 is another modified form of my improved circuit.

Figure 4 is yet another modified form of my improved circuit, and

Figure 5 is a diagram of the resonance curve.

Referring particularly to Figure 1, the numerals 1, 2 and 3 indicaterespectively, the plate, grid and filament of an ordinary threeelectrode vacuum tube. The numeral 4 indicates a low loss coil formed bya few turns of heavy copper wire, while 5 is a variable air condenser oflarge value. The coil and condenser form an oscillating circuit of veryshort period of oscillation, and as shown, are connected directlybetween the plate 1 and the grid 2 of the tube. This oscillating circuitis con led to another oscillating circuit which is o the open type andincludes a coupling coil 6 and two metallic plates 7 having greatsurface. These plates, if desired, can be re laced by a system of wires.It is also possi le to ground one plate. Numerals 8, 9 and 10 indicateordinary radio frequency choke coils introduced in the grid, plate andfilament. circuits respectively. They maintain the grid and filament ata high frequency potential above the point 0 which can be grounded. Thenumerals 11 and 12 indicate by-pass condensers having large value,ranging above one-tenth of a microfarad in this combination. The numeral13 indicates a low tension battery and 14 is a potentiometricarrangement across this battery which neutralizes the plate current in asensitive meter 15. The numeral 16 indicates the winding of anelectro-magnet. 17 is a grid condenser and 18 a grid resistance or gridleak; these two elements being so adjusted that the high frequencyoscillations in the low resistance circuit, 4 and 5, are nearlyannihilated and the plate current maintained at a very low value. Thisis due to periodic charges of the condenser 17 and discharges throughthe resistance, 18.

If the circuit associated with the sensitive plates 7-7 is brought nearresonance to the oscillating circuit, 45, the frequency of the lowfrequency discharges increases and is always followed by an increase inthe plate current. It the coupling of these two circuits is too strongthe low frequency oscillation stops as soon as the open circuit isbrought in resonance; in the same time the plate current jumps to a highvalue and all the sensitivity is lost.

The optimum coupling of the open and closed circuits can be determinedby proper adjustment of the variable condenserfi to a point where thelow frequency oscillation is not stopped.

If the coupling is decreased to an optimum value and the capacity 5varied a resonance curve as shown in Fig. 5 is obtained. The platecurrent starts from a very low value on account of the biasing efiect ofthe grid leak, and increases very rapidly when the resonance isapproached. When using an ordinary tube, the plate current may be variedfrom one milliampere to ten milliamperes or more. If we select as anoperating point, A1 or A2, which are points of inflection on theresonance curve, it is readily understood that extremely smallvariations of C will produce great variations in the plate current.

The external circuit, 677, can also be designed in a great multitude ofvcombinations in order to adapt it to practical requirements. It can betuned to a frequency multiple to the natural frequency of the low lossoscillating circuit, 5. The external circuit can also be composed ofmultiple arrangements coupled to multiple arrangements of the circuit,4-5.

It is also possible to obtain the same results as are obtained with thecircuit shown in Figure 1 by a rearrangement as shown in Figure 2, inwhich the sensitive system, 6-7, is modifiedto a closed circuit and thesystem of plates or wires are attached directly to the plate and denser5.

Either of the circuits indicated above can 'a time interval and grid ofthe tube replacing the conbe so adjusted that a variation of the orderof a micro-microfarad or less in the capacity of the associated systemof plates or wires produces a great variation in the plate current ofthe tube, and so far as I am aware, there is no other existing devicehaving the extreme sensitivity to reactance change which the describedcircuits possess. It is possible to adapt a device of such senitivity tomany practical uses, such as alarm systems, registering and measuringdevices, and remote control apparatus for the operation of mechanicaland electrical sequences.

The relay 16, as shown, may be connected to the high tension or platebattery. lVith the relay may be associated a signal circuit shownconventionally in Fig. 1 as comprising a signalling device 20 and apilot lamp 21 electrically coupled to the system.

The sensitivity of the described arrangement will be appreciated when itis considered that the presence of a man approaching the system of wires(or plates) 7 comprising the external part of the circuit, can bedetected at a distance of ten feet or more. This indication, as has beenexplained, is secured by the change in capacity introduced into thesystem by the approach of an extraneous body. This change in capacitycauses sufficient change in the plate current to actuate an indicatinginstrument as by ringing a hell or operating other equivalent alarmdevices.

The exam le given of the indication of the approach 0 a person is merelyone of the great numberof practical uses to which the device may be put.With a device of such sensitivity it makes it possible to utilize it forthe following pur oses: alarm systems such as burglar, bank, actory andpremise protection systems; counting out production items such asregistering passage of bodies through an'electrostatic field; warningdevices for airplanes to indicate or register their proximity to earthor other obstacles; registering device for indicating the level ofliquid or other fluid or movable bodies; detection of impurities ordefects in insulating materials; measuring device for gauging thethickness of materials of construction; detecting de-v vice forindicating the presence of foreign metallic substances; a traffic signalfor indicating the passage of vehicles at specific points on highways;recording device for counting of people entering theaters, street carsan so' forth; remote control devices for the operation of mechanical orelectrical sequences; specific inductive capacity meters;

capacity meters capable of measuring extremely small capaclties;counting'device or meter device for gas or electrical meters; electricaltiming of races or other events wherein capacity change occur; railroadsignaling; time interval enunciating or recordin systems. In otherwords, as will be appreciated, the device has an extremely wide range ofapplicability and may be utilized effectively, as stated, wherever achange in reactance is introduced into the external system.

The operation of the device will be appreciated from the foregoingdescription. When the device is in operation the grid blocking condenser17 charges and discharges intermittently at a low frequency. The coils8, 9 and 10 are so designed that they produce across the tank circuit,composed of the large capacity 5 and small inductance 4, a drivingelectromotive force of very high frequency. The condensers 11 and 12,being bypass condensers of large value, will not oppose the free passa eof the high frequency oscillation. The p ate element of the tubetherefore is maintained, together with the batteries 13 and 19, atground potential, as shown in the drawings. he potentiometric device 14bucks the plate current flowing from the negative side of the lowpotential or filament battery 13 toward the negative side of the hightension or plate battery 19. This then permits the adjustment of theposition of the needle of the galvanometer to any desired position ofthe scale so that the variations in plate current may be read ratherthan its absolute value.

While I have shown and described the preferred embodiment of myinvention, I wish it to be understood that I do not confine myself tothe precise details of construction herein set forth, by way ofillustration, as it is apparent that many changes and variations may bemade therein, by those skilled in the art, without departing from thespirit of the invention, or exceeding the scope of the appended claims.

I claim:

. 1. In combination, a self-modulated high frequency oscillator of theelectron. tube type comprising a vacuum tube having a filament,

grid and plate, a tank circuit comprising a low inductance, largecapacitance and ow losses connected across the grid and date, a coilbetween the filament and the gri and a second coil between the filamentand plate of the tube.

2. An electrical indicating system comprising an electronic tubeoscillator producing high frequency oscillations modulated at radiofrequency, a tank circuit com )rising a low loss coil and condenserconnected between the plate and grid of the tube, and an openoscillating circuit inductivity coupled to the tank circuit.

3. A high frequenc electronic tube oscillator of the constant requencytype, including a grid circuit comprising a condenser and resistancedischarging at audible frequency, a tank circuit connected between thegrid and the plate, and having small inductance, large capacitance andlow losses, and a plate circuit in which the mean value of the platecurrent is a' function of the reactance of the said tank circuit.

4. A high frequency electronic tube oscillator in which the highfrequency oscillations are modulated at audible frequency, a tankcircuit of low losses connected between the grid and the plate of thetube, and a plate circuit in which the mean value of the current isdependent upon the values of the modulating frequency and an externaloscillating circuit coupled to said tank circuit, and having a naturalfrequency close to the frequency of high frequency oscillations.

5. A high frequency electronic tube oscillator, in which the highfrequency oscillations are modulated at audible frequency, a tankcircuit of low losses connected between the grid and the plate, and aplate circuit in which the mean value-of the current is a function ofthe changes in the reactance of an external oscillating circuit coupledto the tank circuit and tuned to a frequency slightly different from thehigh frequency of the 0scillator.

6. A high frequency electronic tube oscillator adapted to produce highfrequency oscillations modulated at audible frequency, a tank circuit oflow losses connected between the grid and the plate of the tube, anexternal oscillating circuit coupled to the tank circuit and a platecircuit in which the mean plate current under oes large variations whenthe reactance of't e external circuit is slightly changed.

7 A high frequency electronic tube oscillator adapted to produce highfrequency oscillations modulated at audible frequency a tank circuit oflow losses connected between the grid and the plate of the tube, anexternal oscillating circuit coupled to the tank circuit, a platecircuit in which the mean value of the current is a function of thenatural frequency of the external circuit whentuned close to resonanceto said tank circuit.

8. A high frequency electronic tube oscillator producing high frequencyoscillations modulated at audible frequency, a tankcircuit of low lossesconnected between the grid and the plate of the tube, an externaloscillating circuit coupled to the tank circuit, a plate circuitincluding an indicating device showing the variations in the mean valueof the plate current as a function of the variations of reactance of theexternal circuit.

9. A high frequency oscillator of the electronic tube type producing hih frequency oscillations modulated ataudible frequency, a tank circuitof low losses connected between the rid and the plate of the tube, anexternal osci lating circuit coupled to the tank circuit, a platecircuit includin a signal device to indicate the presence 0 a foreignbody approaching the external circuit.

10. A device comprising a high frequency oscillator of the electronictube type adapted to produce high frequency oscillations modulated ataudible frequency, a tank circiut of low losses connected thereto, anexternalcircuit coupled to the tank circuit, and a plate circuitincluding signal devices to detect a variation in the position of masswith respect to the device.

11. A device comprising a high frequency oscillator of the electronictube type producing high frequency oscillations modulating the lowerfrequency, a tank circuit of low losses connected thereto, an externaloscillating circuit coupled to the tank circuit, a plate circuit andmeasuring devices in the plate cir cuit to indicate the position of massrelative to the device.

12. A device comprising a high frequency oscillator of the electronictube type, adapted to produce high frequency oscillations modulated at alower frequency, a tank circuit of low losses connected thereto, anexternal oscillating circuit coupled to the tank circuit, a platecircuit and measuring devices in the plate circuit adapted to show theeffect of the intensity of the stationary electromagnetic field,produced by the reflection of the high frequency wave radiated by theexternal circuit from a conductive mass.

13. A device comprising a high frequency electronic tube oscillator inwhich the high frequency is modulated at audible frequency, a tankcircuit of low losses connected thereto, a plate circuit, means in theplate circuit adapted to show the variation of the intensity of thestationary electromagnetic field established by a radiating circuitcoupled to the tank circuit.

14. An electric device comprising a high frequency oscillator of theelectronic tube type. means to modulate the high frequency oscillationsat audio frequencies, an open oscillating circuit coupled to saidoscillator and tuned to frequency close to the high frequency of theoscillator, and adapted upon variations in its reactance to vary themean value of the plate current of said oscillator. and an electricallyoperated signal coupled to the plate circuit.

15. An electric device comprising a high frequency oscillator of theelectronic tube type, means to modulate the high frequency oscillationsat audio frequencies, an open oscillating circuit coupled to saidoscillator and tuned to frequency close to the high frequency of theoscillator, and adapted upon variations in its reactance to vary themean value of the plate current of said oscillator, and an electricrelay conductively coupled to the plate circuit.

16. An electric device comprising a high frequency oscillator of theelectronic tube constant frequency type, a high frequency oscillatingcircuit connected thereto, means associated directly with the tube tomodulate the high frequency oscillations at audio frequencies includinga blocking condenser and a leak resistance in the grid circuit, meansfor controlling the mean value of the plate current of said oscillatorincluding an open oscillating circuit tuned to a frequency close to thehigh frequency of the oscillator coupled to the said high frequencyoscillating circuit. and means to indicate the variations in said platecurrent.

17. An electric device comprising a bi h frequency. oscillator of theelectronic tu e constant frequency type, a tank circuit of low lossesconnected between the grid and the plate of the tube, said circuitincluding a large capacity and a small inductance, means to modulate thehigh frequencies at audio frequencies including a blocking con denserand a leak resistance placed in the grid circuit, means for controllingthe mean value of the plate current of said tube including an externaloscillating circuit coupled to the tank circuit and having a frequencyclose to the high frequency of the oscillator and means including anindicator in the plate circuit to indicate the value of the platecurrent.

18. A high frequency electronic tube oscillator in which the highfrequency oscillations are modulated at audible frequency, a tankcircuit of low loss connected between the grid and the plate of the tubeand a plate circuit in which the mean value of the current is dependentupon the values of the modulating frequency.

19. In an electrical circuit, a self-modulated high frequency oscillatorof the electronic tube type comprising a filament grid and plate, a tankcircuit including a low inductance, large capacitance and low lossesconnected across the grid and plate, a coil between the filament. andgrid, a second coil between the filament and plate, an external circuitcomprising capacity, inductance and resistance coupled to the tankcircuit, whereby electro-static changes occurring in the coupled circuitproduce reactance changes in the tank circuit. and produce a platecurrent change in the plate circuit of the oscillator.

In testimony whereof I afiix my signature.

CONSTANTIN D. BARBULESCO.

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